Eighty juvenile-onset, insuline-dependent diabetics and 400 adult diabetics on oxogenous insulin or oral agents have been screened and characterized clinically (diabetes history and complications), chemically (diabetes control and mineral metabolsim), and anthropometrically (growth and bone mass). As a group, the young diabetics have diminished bone mass, despite otherwise normal growth, and abnormal mineral metabolism, characterized by low calcium and magnesium and inappropriately low immunoreactive parathyroid hormone. All of the subjects have been enrolled in a prospective study which will enable us to evaluate 1) the relationship, if any, of altered mineral metabolism to diminished bone mass; 2) the relationship of the diabetes syndrome to diminished bone mass and altered mineral metabolism; and 3) the effect of both short-term and long-term improvement in serum glucose control on the diminished bone mass and altered mineral metabolism.